NASA's newest space telescope not only extends astronomers' field of view deeper into the cosmos, it can also reach temperatures as low as never before.
The James Webb Space Telescope (JWST or Webb), the most powerful space observatory to date, has peered deep into a dense molecular cloud and discovered a wide variety of pure interstellar ice, including various chemicals essential to life. These discoveries are the coldest ice ever recorded, discovered at icy temperatures of -263 °C.
According to Klaus Pontoppidan, an astronomer at the Space Telescope Science Institute and co-author of a new study outlining the work, "We wouldn't be able to detect this ice without Webb."
Scientists refer to the region Webb studied as Chameleon I. With dozens of pockets of newborn stars, this region is one of the closest star forming areas and is about 500 light-years from Earth in the southern constellation Chameleon. The region is part of a family of dark molecular clouds that contain gas and dust so dense that visible light from background stars cannot pass through, so astronomers have long believed they are holes in the sky.
Clouds like Chameleon I are star nurseries; When they eventually collapse, stars and perhaps rocky planetary systems are created. But ice embedded deep within the molecular cloud determines the chemical makeup of these systems and the potential life-forming components they may contain.
Now astronomers have looked into Chameleon I's dusty core using Webb's powerful sensors, including its deep-penetrating near-infrared camera (NIRCam), and have seen ice in its early stages of formation, just before the cloud's core collapsed to form protostars.
The team illuminated Chameleon I with infrared radiation from two background stars, NIR38 and J110621. Different infrared wavelengths of sunlight are absorbed by the cloud's various molecules trapped in the ice. Chemical fingerprints, which appeared as dips in the resulting spectrum data, were then studied by astronomers. Using this data, the researchers were able to quantify each molecule in Chameleon I.
According to Would Rocha, another astronomer at the Leiden Observatory, the discovery of methanol showed that the stars and planets that would eventually form in this cloud would "inherit molecules in a highly complex chemical state." This may indicate that the appearance of primitive chemicals in planetary systems is a typical byproduct of star formation rather than a feature of our solar system.
Also, the amino acids that make up proteins can be created by mixing methanol with other, simpler ice. Glycine, one of the simplest amino acids, may be present in these substances. Glycine was discovered in 2016 by Europe's Rosetta probe in dust orbiting comet 67P/Churyumov-Gerasimenko.
Why is it so important to have grains of ice and dust to create habitable exoplanets?
Molecule clouds like Chameleon I start out as hazy regions made up of gas and dust. Ice develops on the surfaces of dust grains, containing chemicals essential for life, including the latest astronomical discoveries.
These ices increase in size while remaining covered in dust grains as the clouds gather in gaseous clumps and move towards star formation. When chemical reactions occur on a solid surface, such as a grain of dust, rather than in a gaseous state, they usually proceed faster and produce the complex molecules necessary for life.
As a result, dust particles play a key role in the transformation of simple organic substances into complex compounds that could one day form the basis of life.
The volatile nature of these ices also allows them to turn back into gases when temperatures rise; in this way they reach the heated cores of stars and then planetary atmospheres. Thanks to the discovery of these pure ices inside Chameleon I, astronomers can trace the journey of compounds from living in dust grains to being incorporated into the cores and atmospheres of potential stars and exoplanets.
Astronomers already know from Webb's data that some elements newly identified in Chameleon I are much less abundant than would be expected given the cloud's density.
For example, only 1% of predicted sulfur, 19% of predicted oxygen and carbon, and only 13% of predicted total nitrogen were found by researchers. The best explanation, according to the researchers, is that these components may be trapped inside other ices that don't show up at the wavelengths the team detected.
In the coming months, the team plans to use Webb's data to determine the size of the dust grains and the shapes of the ice.
According to McClure, these findings "open a new window into the production pathways of simple and complex molecules necessary to produce the building blocks of life."
Source: space – Nature
Günceleme: 25/01/2023 21:23